Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<cstdio>
#include<iostream>
#include<queue>
#include<algorithm>
using namespace std;
typedef pair<int,int> pai;
queue<pai> que;
char c[60][60];
int cnt;
bool flag[60][60];
int ans[60][60];
int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};
int main()
{
	int h,w;
	cin>>h>>w;
	for(int i=0;i<h;i++)
	{
		for(int j=0;j<w;j++)
		{
			cin>>c[i][j];
			if(c[i][j]=='.') cnt++;
		}
	}
	flag[0][0]=true;
	que.push(pai(0,0));
	while(!que.empty())
	{
    pai p=que.front();
    que.pop();
    for(int i=0;i<4;i++)
		{
      int x=p.first+dx[i],y=p.second+dy[i];
      if(0<=x&&x<h&&0<=y&&y<w&&!flag[x][y]&&c[x][y]=='.')
			{
        flag[x][y]=1;
        ans[x][y]=ans[p.first][p.second]+1;
        que.push(pai(x,y));
      }
    }
  }
	cout<<(ans[h-1][w-1]?cnt-ans[h-1][w-1]-1:-1)<<endl;
}